Implement CPUID leaf 0x80000026 (AMD Extended CPU Topology). It presents the
complete topology information to guests via a single CPUID with multiple
subleafs, each describing a specific hierarchy level, viz. core, complex,
die, socket.

Note that complex/CCX level relates to "die" in QEMU, and die/CCD level is
not supported in QEMU yet. Hence, use CCX at CCD level until diegroups are
implemented.

Signed-off-by: Shivansh Dhiman <shivansh.dhiman@amd.com>
---
 target/i386/cpu.c     | 76 +++++++++++++++++++++++++++++++++++++++++++
 target/i386/kvm/kvm.c | 17 ++++++++++
 2 files changed, 93 insertions(+)

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 641777578637..b7827e448aa5 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -495,6 +495,78 @@ static void encode_topo_cpuid1f(CPUX86State *env, uint32_t count,
     assert(!(*eax & ~0x1f));
 }
 
+/*
+ * CPUID_Fn80000026: Extended CPU Topology
+ *
+ * EAX Bits Description
+ * 31:5 Reserved
+ *  4:0 Number of bits to shift Extended APIC ID right to get a unique
+ *      topology ID of the current hierarchy level.
+ *
+ * EBX Bits Description
+ * 31:16 Reserved
+ * 15:0  Number of logical processors at the current hierarchy level.
+ *
+ * ECX Bits Description
+ * 31:16 Reserved
+ * 15:8  Level Type. Values:
+ *       Value   Description
+ *       0h      Reserved
+ *       1h      Core
+ *       2h      Complex
+ *       3h      Die
+ *       4h      Socket
+ *       FFh-05h Reserved
+ * 7:0   Input ECX
+ *
+ * EDX Bits Description
+ * 31:0 Extended APIC ID of the logical processor
+ */
+static void encode_topo_cpuid80000026(CPUX86State *env, uint32_t count,
+                                X86CPUTopoInfo *topo_info,
+                                uint32_t *eax, uint32_t *ebx,
+                                uint32_t *ecx, uint32_t *edx)
+{
+    X86CPU *cpu = env_archcpu(env);
+    uint32_t shift, nr_logproc, lvl_type;
+
+    switch (count) {
+    case 0:
+        shift = apicid_core_offset(topo_info);
+        nr_logproc = num_threads_by_topo_level(topo_info, CPU_TOPOLOGY_LEVEL_CORE);
+        lvl_type = 1;
+        break;
+
+    case 1:
+        shift = apicid_die_offset(topo_info);
+        nr_logproc = num_threads_by_topo_level(topo_info, CPU_TOPOLOGY_LEVEL_DIE);
+        lvl_type = 2;
+        break;
+
+    case 2:
+        shift = apicid_die_offset(topo_info);
+        nr_logproc = num_threads_by_topo_level(topo_info, CPU_TOPOLOGY_LEVEL_DIE);
+        lvl_type = 3;
+        break;
+
+    case 3:
+        shift = apicid_pkg_offset(topo_info);
+        nr_logproc = num_threads_by_topo_level(topo_info, CPU_TOPOLOGY_LEVEL_SOCKET);
+        lvl_type = 4;
+        break;
+
+    default:
+        shift = 0;
+        nr_logproc = 0;
+        lvl_type = 0;
+    }
+
+    *eax = shift & 0x1F;
+    *ebx = nr_logproc;
+    *ecx = ((lvl_type & 0xFF) << 8) | (count & 0xFF);
+    *edx = cpu->apic_id;
+}
+
 /* Encode cache info for CPUID[0x80000005].ECX or CPUID[0x80000005].EDX */
 static uint32_t encode_cache_cpuid80000005(CPUCacheInfo *cache)
 {
@@ -8554,6 +8626,10 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
                                                  R_EBX) & 0xf;
         }
         break;
+    case 0x80000026:
+        /* AMD Extended CPU Topology */
+        encode_topo_cpuid80000026(env, count, topo_info, eax, ebx, ecx, edx);
+        break;
     case 0xC0000000:
         *eax = env->cpuid_xlevel2;
         *ebx = 0;
diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index 60c798113823..ed3d40bf073e 100644
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -2037,6 +2037,23 @@ uint32_t kvm_x86_build_cpuid(CPUX86State *env, struct kvm_cpuid_entry2 *entries,
                 c = &entries[cpuid_i++];
             }
             break;
+        case 0x80000026:
+            /* Query for all AMD extended topology information leaves */
+            for (j = 0; ; j++) {
+                c->function = i;
+                c->flags = KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
+                c->index = j;
+                cpu_x86_cpuid(env, i, j, &c->eax, &c->ebx, &c->ecx, &c->edx);
+
+                if (((c->ecx >> 8) & 0xFF) == 0) {
+                    break;
+                }
+                if (cpuid_i == KVM_MAX_CPUID_ENTRIES) {
+                    goto full;
+                }
+                c = &entries[cpuid_i++];
+            }
+            break;
         default:
             c->function = i;
             c->flags = 0;
-- 
2.43.0